Mister Exam

Sum of series 2k-1



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The solution

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  oo           
 __            
 \ `           
  )   (2*k - 1)
 /_,           
k = 1          
$$\sum_{k=1}^{\infty} \left(2 k - 1\right)$$
Sum(2*k - 1, (k, 1, oo))
The radius of convergence of the power series
Given number:
$$2 k - 1$$
It is a series of species
$$a_{k} \left(c x - x_{0}\right)^{d k}$$
- power series.
The radius of convergence of a power series can be calculated by the formula:
$$R^{d} = \frac{x_{0} + \lim_{k \to \infty} \left|{\frac{a_{k}}{a_{k + 1}}}\right|}{c}$$
In this case
$$a_{k} = 2 k - 1$$
and
$$x_{0} = 0$$
,
$$d = 0$$
,
$$c = 1$$
then
$$1 = \lim_{k \to \infty}\left(\frac{\left|{2 k - 1}\right|}{2 k + 1}\right)$$
Let's take the limit
we find
True

False
The rate of convergence of the power series
The answer [src]
oo
$$\infty$$
oo
Numerical answer
The series diverges
The graph
Sum of series 2k-1

    Examples of finding the sum of a series